1. Field of the Invention
The present invention relates to an information processing apparatus for processing information according to a predetermined control program.
2. Related Background Art
In a printing apparatus which is one of the conventionally known apparatus of this kind, a predetermined control program is stored for example in an internal ROM, for controlling the apparatus.
Also in a conventional second printing apparatus, a command analyzing routine is separated from the stored program and stored in a detachable program memory medium, and plural command analyzing routines are selectively called by the main routine of a control program incorporated in the main body of the printing apparatus, whereby an apparatus can effect the printing operation according to plural command systems.
Also in a conventionally known third printing apparatus, a control program, independently executable from the control program incorporated in the printing apparatus, is stored in a detachable program cartridge, and the start-up process of the apparatus selects either to execute the control program stored on the program cartridge or to execute the incorporated program.
The program cartridge is common in shape with the font cartridge storing character dot patterns, and such cartridges have identification information indicating "program" or "font information". The incorporated control program shifts the control to the program of the cartridge only when it bears the identification information for "program".
However, the first conventional example mentioned above can only execute a predetermined control program, and is unable to effect the printing operation according to any other command system.
The second conventional example can adapt itself to other plural command systems, but is incapable of processes other than command analysis (changes in the control of apparatus, such as a change in the hand shake process with a data source such as a host computer, or a change or an addition in the sheet handling of the printing mechanism in a jamming process), because the main routine of the control program is incorporated in the apparatus. For this reason there is inevitably a limitation in the utilization of various printing functions by an apparatus.
Also in the third conventional example, once the execution of a control program is started, the switching of program is difficult because the other control program is so designed as to function independently from the one in execution.
Besides, in the third example, the control program on the program cartridge, which functions properly on a certain apparatus, may not function properly on another apparatus because of the difference in hardware. Consequently there is a danger that a program which does not function properly may be executed because no means is provided for identifying whether the program is proper or not.
Also in case there are certain differences in the control among plural printing apparatus, no means is provided for identifying the properly functioning programs among plural cartridges provided for each apparatus, so that an improper control program may be executed on a certain apparatus.